Piano-style keypad employing a light guide

Abstract

An improved piano-style keypad comprises a light guide and a key sheet, with the light guide retaining the key sheet on a substrate, such as a printed circuit board of a handheld electronic device. The keypad is advantageously configured to enable key caps of the keypad to be adhered to key bodies of the keypad in a fashion that provides long-term reliability while still providing keys that can readily actuated and that provide tactile feedback that is desirable to the user.

1. A keypad for a handheld electronic device that comprises a light source, the keypad comprising:
 a key sheet comprising a base and a number of key bodies, at least some of the key bodies each being disposed on the base and being movable between an unactuated position and an actuated position, the key body in the actuated position being structured to complete a circuit of the handheld electronic device, at least a portion of the key sheet being translucent; and 
 a light guide comprising a frame and a number of supports, at least some of the supports extending in a common direction from the frame, at least a portion of the frame being disposed adjacent at least a portion of the base, at least some of the supports each engaging the base and being structured to resist movement of the base in a direction transverse to the common direction, at least a portion of the light guide being translucent and being structured to transmit light between the light source and the key sheet, 
 wherein the base comprises a web and a leg network, the leg network protruding from the web and being structured to engage a substrate of the handheld electronic device, a portion of the web peripheral to a particular key body being movable between an undeflected position and a deflected position, the portion of the web being in the undeflected position when the particular key body is in the unactuated position, the portion of the web being in the deflected position when the particular key body is in the actuated position. 
 
     
     
       2. The keypad of  claim 1  wherein the key sheet comprises a number of receptacles, at least some of the supports each being received in a receptacle. 
     
     
       3. The keypad of  claim 2  wherein the receptacles are holes formed in the base, and wherein the supports are pegs that protrude from the frame and that are received in the holes. 
     
     
       4. The keypad of  claim 3  wherein at least some of the pegs each have an interference fit with a hole. 
     
     
       5. The keypad of  claim 1  wherein the leg network comprises a plurality of braces structured to engage the substrate, the braces being structured to resist movement of a portion of the web peripheral to one key body toward its undeflected position when a portion of the web peripheral to an adjacent key body moves toward its deflected position. 
     
     
       6. The keypad of  claim 5  wherein at least some of the braces each have a hole formed therein, and wherein the supports are pegs that are received in the holes, at least some of the key bodies being movable along the common direction between the unactuated and actuated positions. 
     
     
       7. The keypad of  claim 1  wherein the key sheet further comprises a number of key caps, at least some of the key caps each being adhered to a key body. 
     
     
       8. The keypad of  claim 7  wherein the frame has a number of openings formed therein, at least some of the key bodies each being disposed within an opening. 
     
     
       9. The keypad of  claim 7  wherein at least a portion of the frame is disposed between the base and the key caps. 
     
     
       10. A keypad for a handheld electronic device that comprises a light source, the keypad comprising:
 a key sheet comprising a base a number of key bodies, and a number of key caps, at least some of the key bodies each being disposed on the base and being movable between an unactuated position and an actuated position, the key body in the actuated position being structured to complete a circuit of the handheld electronic device, at least some of the key caps each being adhered to a key body, at least a portion of the key sheet being translucent; and 
 a light guide comprising a frame and a number of supports, at least a portion of the light guide overlying at least a portion of the base, at least a portion of the frame being disposed between the base and the key caps, at least a portion of the light guide being translucent and being structured to transmit light between the light source and the key sheet. 
 
     
     
       11. The keypad of  claim 10  wherein the light guide has a number of openings formed therein, at least some of the key bodies each being disposed within an opening. 
     
     
       12. The keypad of  claim 11  wherein the openings are formed in the frame. 
     
     
       13. The keypad of  claim 10  wherein the base comprises a web and a leg network, the leg network protruding from the web and being structured to engage a substrate of the handheld electronic device, a portion of the web peripheral to a particular key body being movable between an undeflected position and a deflected position, the portion of the web being in the undeflected position when the particular key body is in the unactuated position, the portion of the web being in the deflected position when the particular key body is in the actuated position. 
     
     
       14. The keypad of  claim 13  wherein at least a portion of the web is disposed between the leg network and at least a portion of the light guide. 
     
     
       15. The keypad of  claim 14  wherein the portion of the web peripheral to the particular key body extends between the particular key body and at least a portion of the leg network. 
     
     
       16. A keypad for a handheld electronic device that comprises a light source, the keypad comprising:
 a substrate; 
 a light guide comprising a frame, a number of supports, and a number of retention members, the number of supports and the number of retention members extending in a common direction from the frame, at least some of the retention members each being engaged with the substrate; 
 a key sheet comprising a base and a number of key bodies, at least some of the key bodies each being disposed on the base and being movable between an unactuated position and an actuated position, the key body in the actuated position being structured to complete a circuit of the handheld electronic device, at least a portion of the key sheet being disposed between at least a portion of the light guide and at least a portion of the substrate, at least some of the supports each engaging the base and being structured to resist movement of the base in a direction transverse to the common direction, at least a portion of the key sheet being translucent; and 
 at least a portion of the light guide being translucent and being structured to transmit light between the light source and the key sheet. 
 
     
     
       17. The keypad of  claim 16  wherein at least some of the retention members each comprise a latch that is engaged with the substrate. 
     
     
       18. The keypad of  claim 16  wherein the base has a number of holes formed therein, and wherein the supports are pins received in the holes. 
     
     
       19. The keypad of  claim 16  wherein the key sheet further comprises a number of key caps, at least some of the key caps each being adhered to a key body. 
     
     
       20. The keypad of  claim 19  wherein the frame has a number of openings formed therein, at least some of the key bodies each being disposed within an opening. 
     
     
       21. The keypad of  claim 19  wherein at least a portion of the frame is disposed between the base and the key caps.